Hurricane Irene downed power lines and flooded substations, knocking out electricity to to more than 800,000 New Jersey homes and businesses by 2:00 this afternoon, as utility companies around the state scatter to respond to damage.

Public Service Electric & Gas reported about 330,000 customers without power.

Jersey Central Power & Light reported 373,000 outages, with 246,000 in the area of Monmouth, Ocean and Middlesex counties.

"We have a couple substations that are flooded," said spokesman Ron Morano. "One is in Morristown. It's near the Whippany River, and there was a wall built to protect it, and the river exceeded it. That's the type of thing we're seeing, and there's a lot of damage."

PSE&G said its crews and tree contractors are working around the clock but warned customers to be ready for lengthy outages.

Atlantic City Electric reported new highs for the day of nearly 1,900 outages, with 105,000 customers affected.

The power outages and flooding caused some water treatment facilities to stop working. Many towns are advising residents to boil water: Florham Park, Irvington, Maplewood, Millburn, Short Hills, Springfield, Summit, West Orange, Hightstown, Rockaway Township, and South Amboy. More are likely to come.

Meanwhile, the danger of inland flooding is increasing as rivers continue to swell. Even as parts of the state come back to life, Gov. Chris Christie is urging residents to remain home.

“The real issue we will have to deal with is flooding," Christie said. “I cannot urge people enough — maybe I can — stay home today.”

Some New Jersey waterways are predicted to reach record levels, Christie said. Some towns are expected to be inundated by dangerous and damaging floods.

The winds may still knock over trees and down power lines, he added.

Flood waters will drive up the Ramapo River near the Pompton Lake dam by an anticipated 19.2 feet, breaking a 1984 record when the water climbed to 18 feet, Christie told reporters at his first media briefing today at State Police headquarters in Ewing.

The Ramapo River in Pompton Plains could crest as high as 24 feet — matching a flood record from 1984, Christie said.

Gov. Christie: Storm wasn't as bad as expectedHours after Hurricane Irene left New Jersey, Gov. Chris Christie said the storm's damage wasn't as bad as expected. Still, flooding is a huge issue, there are still thousands in shelters and without power. (Megan DeMarco/The Star-Ledger)

“The DEP (Department of Environmental Protection) already has engineers on the way to the most vulnerable dams,” he said. “This includes Solitude Dam in High Bridge, Hunterdon County, where residents have been evacuated.”

Traffic is once again flowing southbound on the southern portion of the Garden State Parkway, which had been closed south of Exit 98 during Hurricane Irene.

Even as the state sends New Jersey Transit buses to take 15,000 evacuees home from 53 shelters, Gov. Christie said they may have to open new shelters in schools if flooding necessitates it.

Meanwhile, state officials are just starting to get an idea of the damage Irene left in her wake.

At least three deaths have been attributed to the storm.

In Kearny, a man drowned, but police have offered few details.

In Edison, a 74-year-old man died of a heart attack in his flooded basement, according to the Middlesex County Office of Emergency Management.

Video of damage from a possible tornado from Hurricane Irene in Long BranchA possible tornado spawned by Hurricane Irene cut a swath of damage through a Long Branch neighborhood, downing power lines and trees, shattering windows and blowing roofs off buildings. Vine Court Resident Frank Schwartz was lying in bed when a section of his neighbor's roof crashed through the window. He awoke covered in in glass. There were no severe injuries in the neighborhood from the storm. (Video by Brian Donohue/The Star-Ledger)

And in Salem County, 20-year-old Celena Sylvestri , who had called 911 after her car was swept away by flood waters, was found dead at 9:30 this morning.

Gov. Christie, at a press conference this afternoon, said that a firefighter in Princeton “succumbed to his injuries from an attempted swift water rescue.”

But Maria Comella, spokesman for the governor, confirmed the man is actually still alive.

"The Governor was given inaccurate information and it has been confirmed that the Princeton firefighter is alive and in critical condition in the ICU," Comella said in a statement. The 39-year-old man is not actually a firefighter but a 39-year-old volunteer with First Aid & Rescue, a group independent of the fire department Princeton Township Police Sgt. Michael Cifelli said.

New details emerged this afternoon on Sylvestri, who was the first reported death from the storm. She had been driving on Route 40 in Pilesgrove at 1:40 am when she first contacted her boyfriend for help, and then dialed 911, State Police Sgt. Brian Polite said.

The State Police swat team arrived and encountered fast-rising waters on the roadway. Divers searched, tethering themselves with a rope, Polite said. While looking for her, they rescued someone James Troy, 68, of Cape May, who has been treated and released from the hospital .

Troopers finally found Silvestri’s submerged car, a gray Honda Accord, 150 feet off the roadway at 9:30 am, Polite said. She was dead.

Video: State Police attempted to rescue 20-year-old Salem womanSgt. Brian Polite of the State Police said a 20-year-old Salem woman called police last night. On their way to find her, divers rescued another man who was submerged. They couldn't find the woman, whose body was recovered this morning. (Megan DeMarco/The Star-Ledger)

“When they went out the first time, it was pretty much flash-flood conditions, I don’t know exactly how high,” Polite said. “These are brave troopers and it was not the safest environment for them to be out there looking for an extended period of time.”

It was unclear whether her car was found in a body of water or on the road.

Polite described the information as “preliminary,” saying the rescue team was so busy, “they are just going from location to location.”

In Manville, which was swamped with flood waters, a woman went into labor and had to be rescued by boat, according to Manville Director of Emergency Management Ken Otrimski. Attempts to airlift the unidentified woman out were thwarted because a helicopter could not land in the high winds, Otrimski said.

An ambulance took her as far as the Manville side of the Van Veghten Bridge, where rescue workers then boated her across the river to an ambulance on the other side. On their way back, though, the boat stalled and rescue workers had to row to shore and tie to a tree to await rescue from another boat, which eventually towed them back to safety.